The second approach uses Object.values, which when passed an object will return you an array containing the values of the object. If you have an id or some other unique value for each of the values, awesome! But if you don't, this approach has some downfalls as you may not have acces...
frenchRoast, decaf];varcoffeeSizes = [small, medium, large];// build new objects that are combinations of the above// and put them into a new arrayvarcoffees = coffeeTypes.reduce(function(previous, current) {varnewCoffee = coffeeSizes.map(function(mixin) {// `plusmix` function for funct...
const data=[{filterKey:'name',filterValue:[{value:'abc'},{value:'def'}]},{filterKey:'status',filterValue:[{value:'active'},{value:'pending'}]}]; // Iterate over the array with `reduce` const out = data.reduce((acc, obj) => { // Extract the key and value from each object ...
to iterate over arrays, and Object.keys() / Object.values() / Object.entries() to produce arrays so you can iterate over objects. const numbers = [1, 2, 3, 4, 5]; // bad let sum = 0; for (let num of numbers) { sum += num; } sum === 15; // good let sum = 0; ...
构造函数本身就是一个函数，用于创建新对象。 var person = new Object();这行代码创建了一个Object的...
to iterate over arrays, and Object.keys() / Object.values() / Object.entries() to produce arrays so you can iterate over objects. const numbers = [1, 2, 3, 4, 5]; // bad let sum = 0; for (let num of numbers) { sum += num; } sum === 15; // good let sum = 0; ...
For-of 循环 Promises 模块 String 新方法 Object 新方法 展开运算符 Set Map Generators ES2016 Array.prototype.includes() 求幂运算符 ES2017 字符串填充 Object.values() Object.entries() Object.getOwnPropertyDescriptors() 尾逗号 共享内存 and 原子操作 ...
to iterate over arrays, and Object.keys() / Object.values() / Object.entries() to produce arrays so you can iterate over objects. const numbers = [1, 2, 3, 4, 5]; // bad let sum = 0; for (let num of numbers) { sum += num; } sum === 15; // good let sum = 0; ...
Classes New syntax supports declaration of classes. Promises Promises allow easier and cleaner asynchronous coding. Promise constructors are supported, along with the all and race utility methods. Iterators Now you can iterate over iterable objects (including arrays, array-like objects, and iterators)...
Every page contains an array of table names, so in this case, to iterate over every single table name we can simply use for...of. In general, we can use the for await...of syntax with objects that are async iterable. In the next few sections, we will see how JavaScript classifies ...